Electric cable



June 17, 1941. G. M. GIANNINI 2,245,771

ELECTRIC CABLE Filed May 2, 1939 INVENTOR. GABRIEL M. GIANNINI BY Xfflfluddafi ATTORNEY.

'and mechanical characteristics.

Patented June 17, 1941 2,245,771 ELEc'raIc CABLE Gabriel Maria Giannini, Great Neck, N. Y., as-, signor to Transducer Corporation, New York, N. Y., a corporation or New York Application May 2, 1939, Serial No. 271,333

3 Claims.

My invention relates to electric cables and more particularly to flexible coaxial cables for the transmission of high-frequency current.

Although numerous constructions for coaxial cables have been suggested, in general such constructions either do not have the desired degree flexibility or do not have the desired electrical I More particularly, ii the outer hollow conductor is made flexible, for instance of woven wire, and the central conductor is supported therefrom by a plurality of interspaced discs of insulating material, these discs must be spaced very close together in order to prevent the hollow conductor from collapsing. As a result the space between the central conductor and the hollow conductor is for the most part occupied by the discs of insulating material, which, as is well known, does not have the'dielectric properties ofair.

The main object of my invention is to produce a coaxial cable which is highly flexible and at the same time has excellent electrical properties and retains these properties when it is bent into various shapes.

A further object of my invention is to provide a flexible coaxial cable in which air forms the major part 01' the insulation between the central and inexpensive manner.

A still further object is a cable in'which the central'conductor can be readily replaced.

A further object is to provide a construction in which the assembly of central conductor, insulators and hollow supporting member can be readily inserted into a stationary tubular outer conductor and withdrawn therefrom.

Further objects and advantages of my novel cable will appear as the description progresses.

be understood to mean a hollow body formed by an elongated metal member which extends in one direction over an arc of about 360, extends axially a short distance, and then reverses its direction and extends inthe opposite direction over a similar arc, etc.

In such a reverse spiral annular spaces are formed between adjacent turns, and I have found that the insulating discs which serve to support the central conductor can be advantageously supported if their edges fit into these spaces. In addition there is an axially-extending space formed in the reverse spiral," and by providing the. insulating discs with radial grooves it is possible to insert the central conductor after the insulating discs and hollow conductor have been assembled, or to replace the central conductor.

In order that the invention may be clearly understood and readily carried into effect, I shall describe thesame in more detail with reference to the accompanying drawing, in which,

Figure l is a perspective view, with certain I parts removed, of a coaxial cable according to the invention,

Fig. 2 is a front view of one of the insulating discs of Figure 1,

Fig. 3 is a side view of the disc of Figure 2,

Fig. 4 is a side view of an insulating disc according to another embodiment of the'invention,

Fig. 5 is a development of the flexible hollow supporting member of Figure 1,

Fig. 6 is a plan view of a flexible support according to another embodiment of the invention,

In accordance with the invention I use a flexible hollow supporting member in the form oi a "reverse spiral and support the central conductor from this spiral by a plurality of inter-spaced members of insulating material. This spiral may act as the hollow conductor, or if desired it may be covered by a separate conductor in the form of a flexible metal tube, for instance of woven wire.

The term reversespiral as used herein is to and Fig. 7 is a development of the support of Fig. 6.

The coaxial cable shown in Figure 1 comprises a flexible hollow s pporting member I consisting of a metal wire, for instance a steel wire, formed in the shape of a "reverse spiral, As shown at the lower end of the figure, the wire extends counterclockwise over a, circular arc of slightly less than 360, extends in an axial direction a tance a may be between about one to ten times )7 the diameter of the hollow supporting member. The hollow supporting member I is shown in development in Figure 5.

2 are a plurality of discs 5 of insulating material,

- lar ridge 1 provided with a notch 8. When the discs are assembled in the hollow supporting member 11' (see Figure 1), the ridge 1 fits snugly between adjacent turns of the reverse spiral and the axially-extending portion of the spiral fits into notch 8 to thereby prevent rotation of the WhatI claim is:

1. A flexible cable comprising a hollow sup-'- porting member formed of an elongated metal member, said supporting member having a plurality of similar portions each formed by said metal member extending clockwise over a circular arc of approximately 360, extending axidiscs and hold the discs firmly in the proper position. From Figure 1 it will be noted that the discs G can be spaced at a) considerable distance apart andthe air forms the major portion of the insulation.

Instead of using in the cable of Figure 1, insulating discs of the type shown in Figures 2 and 3, it is possible to use discs H) such as shown in Figure 4. The disc I0 is the same'as the disc 6 shown in Figures 2 and 3 except that it is provided with a notch 96 and a radially-extending slot H, whose sides are at an angle to the axis of the central hole l2. When such discs are used in Fig. 1 it is possible to insert the conductor 6 through the axially-extending space 3 and Instead of forming the hollow supporting. member 9 from wire it-may be stamped from metal and such a construction is illustrated in Figures 6- and 7. As shown in Figure 7, a fiat member 65 of serpentine shape. is stamped from I .a sheet of-metal. This metal is then bent into a tubular shape, as shown in Figure 6, which serves as the hollow supporting member.

While I have described my invention with reference to certain applications and specific structural details, I do not wish-to be limited thereto because obvious modifications will readily occur to one skilled in this art.

ally a short distance, extending counterclockwise over a circular arc of approximately 360 and then extending axially a short distance, a conductpr within said hollow member, and a pinrality of inter spaced members of insulating material supported by the circular arc portions of said hollow member and supporting said conductor. v

2. A fiexiblecable comprising a hollow supporting member formed of an elongated metal member, said supporting member having a plurality of similar portions each. formed by said metal member extending clockwise over a circular arc of approximately 360, extending axially a short distance, extending counterclockwise over a circular arc of approximately 360and then extending axially a short distance, a conductor within said hollow member, and a plurality of interspaced discs of insulating material supported by said hollow member and supporting'said conductor, each of said discs having a peripheral ridge fitting between adjacent circular portions of said metal member. 1

3. A flexible cable comprising; a hollow supporting member formed of an elongated metal member, said supporting member havinga plurality of similar portions each' formed by said metal member extending clockwise over a circular arc of approximately 360, extending axially a short distance, extending counterclockwise over a circular arc of approximately 360 and then extending axially a shortdistance, a conand provided with a transverse notch engaged by an axially-extending portion of the metal member.

GABRIEL M. GIANNINI. 

